No abstract

A series of N-heterocyclic carbene Au(NHC)Cl complexes (NHC = IMes (1), SIMes (2), IPr (3), SIPr (4), IPrMe (5), IMe (6), ICy (7), IAd (8), ITPh (9)) have been synthesized either through reaction of the corresponding imidazol-2-ylidene carbene with [Au(SMe2)Cl] or by transmetalation of the respective Ag(I)−NHC complex in the presence of 1 equiv of [Au(SMe2)Cl]. All of the gold(I) complexes [Au(IMes)Cl] (10), [Au(SIMes)Cl] (11), [Au(IPr)Cl] (12), [Au(SIPr)Cl] (13), [Au(IPrMe)Cl] (14), [Au(IMe)Cl] (15), [Au(ICy)Cl] (16), [Au(IAd)Cl] (17), and [Au(ITPh)Cl] (18) have been characterized spectroscopically and structurally by X-ray diffraction. The 13C chemical shifts of the carbene carbon have been compared through subtraction of the corresponding imidazol-2-ylidene carbene and suggest that there is little difference in donor ability of the NHC ligands bound to gold(I). Crystal structure analysis reinforces this notion, with no obvious change in Au−C(NHC) bond length on going from saturated and unsaturated NHC ligands. For complexes 14, 17, and 18 Au···H−C interactions were observed from the sidearm substituents on the NHC ligand. Furthermore, the triazolium complex 18 also contains Au···Au interactions as well as head-to-tail π−π stacking of the phenyl sidearm substituent from neighboring molecules.

A series of N-heterocyclic carbene (NHC)AgCl complexes [NHC = SIMes (1), IPr (2), SIPr (3), IPrMe (4), IMe (5), ICy (6), IAd (7), IsB (8), IDD (9), and TPh (10)] have been synthesized through reaction of the imidazolium chloride salts with Ag2O or by direct metalation of the corresponding imidazol-2-ylidene carbene in the presence of AgCl. All silver(I) complexes [(SIMes)AgCl] (11), [(IPr)AgCl] (12), [(SIPr)AgCl] (13), [(IPrMe)AgCl] (14), [(IMe)AgCl] (15), [(ICy)AgCl] (16), [(IAd)AgCl] (17), [(IsB)AgCl] (18), [(IDD)AgCl] (19), and [(TPh)AgCl] (20) have been spectroscopically and structurally characterized. The structure of these silver complexes is dependent on the halide and the solvent used for the synthesis. Adjusting these parameters has led to the previously reported complex, [(IMes)2Ag]+[AgCl2]- (21), and to a new silver complex, [(IMes)2Ag]+ 2[Ag4I6]2- (22).